Atualizar contêineres web e de dados falha em rake db:migrate com PG::ConnectionBad

Tentei atualizar meu Discourse para a versão mais recente usando o comando ./launcher rebuild mywebcontainer. Isso falhou, veja o log abaixo. Tentei resolver removendo todos os plugins da minha configuração em YAML, mas não funcionou. Reconstruir o contêiner de dados funcionou, mas não mudou nada.

Gems in the group development were not installed.
Bundled gems are installed into `./vendor/bundle`

I, [2018-09-13T13:25:54.831348 #15]  INFO -- : > cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate'
rake aborted!
ActiveRecord::StatementInvalid: PG::ConnectionBad: PQconsumeInput() server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
: SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace WHERE n.nspname = ANY (current_schemas(false)) AND c.relname = 'schema_migrations' AND c.relkind IN ('r')
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/patches/db/pg.rb:92:in `async_exec'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/patches/db/pg.rb:92:in `async_exec'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:63:in `block (2 levels) in query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:62:in `block in query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:579:in `block (2 levels) in log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:578:in `block in log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/notifications/instrumenter.rb:23:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:569:in `log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:61:in `query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/database_statements.rb:89:in `query_values'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:61:in `table_exists?'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/schema_migration.rb:22:in `table_exists?'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/schema_migration.rb:26:in `create_table'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1187:in `initialize'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1036:in `new'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1036:in `up'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1011:in `migrate'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/tasks/database_tasks.rb:172:in `migrate'
/var/www/discourse/lib/migration/safe_migrate.rb:30:in `migrate'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/railties/databases.rake:60:in `block (2 levels) in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'

Caused by:
PG::ConnectionBad: PQconsumeInput() server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/patches/db/pg.rb:92:in `async_exec'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/patches/db/pg.rb:92:in `async_exec'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:63:in `block (2 levels) in query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:62:in `block in query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:579:in `block (2 levels) in log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:578:in `block in log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/notifications/instrumenter.rb:23:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract_adapter.rb:569:in `log'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:61:in `query'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/database_statements.rb:89:in `query_values'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:61:in `table_exists?'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/schema_migration.rb:22:in `table_exists?'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/schema_migration.rb:26:in `create_table'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1187:in `initialize'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1036:in `new'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1036:in `up'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/migration.rb:1011:in `migrate'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/tasks/database_tasks.rb:172:in `migrate'
/var/www/discourse/lib/migration/safe_migrate.rb:30:in `migrate'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/railties/databases.rake:60:in `block (2 levels) in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)
I, [2018-09-13T13:26:03.207459 #15]  INFO -- :


FAILED
--------------------
Pups::ExecError: cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate' failed with return #<Process::Status: pid 373 exit 1>
Location of failure: /pups/lib/pups/exec_command.rb:112:in `spawn'
exec failed with the params {"cd"=>"$home", "hook"=>"bundle_exec", "cmd"=>["su discourse -c 'bundle install --deployment --verbose --without test --without development --retry 3 --jobs 4'", "su discourse -c 'bundle exec rake db:migrate'", "su discourse -c 'bundle exec rake assets:precompile'"]}
e240886c64e02acc5030a9b935f4a3768d2ab7621d35e2be0e2090ae51b08b78
** FAILED TO BOOTSTRAP ** please scroll up and look for earlier error messages, there may be more than one

Found it, for some reasons there were multiple web container running.

Interesting, so your actual error was

PG::ConnectionBad: PQconsumeInput() server closed the connection unexpectedly